A review of the geologic history of the Himalayan-Tibetan orogen suggests that at least 1400 km of north-south shortening has been absorbed by the orogen since the onset of the Indo-Asian collision at about 70 Ma. Significant crustal shortening, which leads to eventual construction of the Cenozoic Tibetan plateau, began more or less synchronously in the Eocene (50–40 Ma) in the Tethyan Himalaya in the south, and in the Kunlun Shan and the Qilian Shan some 1000–1400 km in the north. The Paleozoic and Mesozoic tectonic histories in the Himalayan-Tibetan orogen exerted a strong control over the Cenozoic strain history and strain distribution. The presence of widespread Triassic flysch complex in the Songpan-Ganzi-Hoh Xil and the Qiangtang terranes can be spatially correlated with Cenozoic volcanism and thrusting in central Tibet. The marked difference in seismic properties of the crust and the upper mantle between southern and central Tibet is a manifestation of both Mesozoic and Cenozoic tectonics. The form...

Geologic Evolution of the Himalayan-Tibetan Orogen

The thermodynamic properties of 154 mineral end-members, 13 silicate liquid end-members and 22 aqueous fluid species are presented in a revised and updated data set. The use of a temperature-dependent thermal expansion and bulk modulus, and the use of high-pressure equations of state for solids and fluids, allows calculation of mineral–fluid equilibria to 100 kbar pressure or higher. A pressure-dependent Landau model for order–disorder permits extension of disordering transitions to high pressures, and, in particular, allows the alpha–beta quartz transition to be handled more satisfactorily. Several melt end-members have been included to enable calculation of simple phase equilibria and as a first stage in developing melt mixing models in NCKFMASH. The simple aqueous species density model has been extended to enable speciation calculations and mineral solubility determination involving minerals and aqueous species at high temperatures and pressures. The data set has also been improved by incorporation of many new phase equilibrium constraints, calorimetric studies and new measurements of molar volume, thermal expansion and compressibility. This has led to a significant improvement in the level of agreement with the available experimental phase equilibria, and to greater flexibility in calculation of complex mineral equilibria. It is also shown that there is very good agreement between the data set and the most recent available calorimetric data.

An internally consistent thermodynamic data set for phases of petrological interest

Two end member models of how the high elevations in Tibet formed are (i) continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and (ii) time-dependent, localized shear between coherent lithospheric blocks. Recent studies of Cenozoic deformation, magmatism, and seismic structure lend support to the latter. Since India collided with Asia ∼55 million years ago, the rise of the high Tibetan plateau likely occurred in three main steps, by successive growth and uplift of 300- to 500-kilometer-wide crustal thrust-wedges. The crust thickened, while the mantle, decoupled beneath gently dipping shear zones, did not. Sediment infilling, bathtub-like, of dammed intermontane basins formed flat high plains at each step. The existence of magmatic belts younging northward implies that slabs of Asian mantle subducted one after another under ranges north of the Himalayas. Subduction was oblique and accompanied by extrusion along the left lateral strike-slip faults that slice Tibet's east side. These mechanisms, akin to plate tectonics hidden by thickening crust, with slip-partitioning, account for the dominant growth of the Tibet Plateau toward the east and northeast.

http://science.sciencemag.org/content/sci/294/5547/1671.full.pdf

Oblique Stepwise Rise and Growth of the Tibet Plateau

The thermodynamic properties of 254 end-members, including 210 mineral end-members, 18 silicate liquid end-members and 26 aqueous fluid species are presented in a revised and updated internally consistent thermodynamic data set. The PVT properties of the data set phases are now based on a modified Tait equation of state (EOS) for the solids and the Pitzer & Sterner (1995) equation for gaseous components. Thermal expansion and compressibility are linked within the modified Tait EOS (TEOS) by a thermal pressure formulation using an Einstein temperature to model the temperature dependence of both the thermal expansion and bulk modulus in a consistent way. The new EOS has led to improved fitting of the phase equilibrium experiments. Many new end-members have been added, including several deep mantle phases and, for the first time, sulphur-bearing minerals. Silicate liquid end-members are in good agreement with both phase equilibrium experiments and measured heat of melting. The new dataset considerably enhances the capabilities for thermodynamic calculation on rocks, melts and aqueous fluids under crustal to deep mantle conditions. Implementations are already available in thermocalc to take advantage of the new data set and its methodologies, as illustrated by example calculations on sapphirine-bearing equilibria, sulphur-bearing equilibria and calculations to 300 kbar and 2000 °C to extend to lower mantle conditions.

An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids

[1] The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ∼1% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire ∼1000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2-year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products.

/pdf/mars-reconnaissance-orbiter-s-high-resolution-imaging-4bjw0ks5y9.pdf

Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE)

This special double issue of Geofluids marks both the tenth anniversary of the launch of the journal and the first volume to appear only online. Geofluids has truly tracked a fundamental change in the nature of scientific publication. For this issue, we sought to bring together a collection of papers spanning a range of topics to which the role of fluids in the Earth is central. Geofluids was founded to help emphasise the common ground between fluid processes that take place in different geological settings, and to provide an outlet for research that considers the interactions of chemical and physical processes. While we cannot pretend to provide a comprehensive coverage of all the important recent advances, we are delighted to have been able to bring together some excellent and wide-ranging new science that continues in this tradition. The first four articles all concern our fundamental theoretical and experimental understanding of essentially aqueous fluids. Liebscher provides an overview of the properties of water-rich fluid systems and how these are affected by solutes, while noting the remaining limitations in the experimental database. Dolejs and Manning present the first comprehensive study to produce a more flexible alternative to the HKF model for aqueous electrolytes, better suited to the range of compositions and conditions encountered in nature, while Sherman shows how modern computational power means that some fundamental problems in natural fluid chemistry can be addressed from first principles using quantum chemistry and molecular dynamics. In the final article in this section, Newton and Manning review recent experimental results for lower crustal conditions and present new data to quantify the importance of dissolved salts for the solubility of the major rock –forming elements, Si and Al, and for a range of important Ca-minerals. The second group of articles relate to a specific geological setting where fluid processes are of the highest importance: sedimentary basins. Parnell provides a concise review of the use of hydrocarbon fluid inclusions to understand the evolution of reservoirs through time and the relationships between fluid stages and mineral cements. He shows in particular how this approach has contributed to understanding the oil charge history of the North Sea and UK Atlantic margin. Hanor and Mercer describe the behaviour of saline waters and their distribution in the Gulf of Mexico, and show how salinity differences arising through salt dissolution can dictate flow patterns. They also explore the likely impacts of salt on the potential of the region as a source of methane hydrates. The article by Manzocchi, Childs and Walsh reviews how faults affect the flow of fluids, in particular hydrocarbons, in siliciclastic basins, and also comment on the extent to which current industry practice for evaluating the effects of faults is actually grounded in science. A third group of article deals with fluid processes in oceanic settings. Saffer has modelled the lateral variations along the Nankai margin of Japan and shown that large scale variations along strike in the taper angle of the accretionary wedge can be linked back to lithological variations from more turbidite-rich sequences to mudrocks. The lithology affects the development of fluid overpressure and the draining of the subduction zone fault, which in turn influences the overall geometry of the wedge. The interplay between permeability, heat flow and discharge characteristics at mid-ocean ridges is explored by Driesner. His results support some findings from terrestrial geothermal systems: high temperature discharges, and the highest fluid salinities, may be associated with low fluid fluxes, while large discharges at relatively low temperatures may in fact dominate the removal of heat. Fisher and Harris take three specific examples of mid-ocean ridge settings to explore the controls on heat loss. The relative importance of conductive heat loss is variable, and specific features of the basement geology can serve to target fluid flow and hence heat loss. Hydrothermal vents are also of likely significance for both abiotic and metabolic organosynthesis and this is explored by Shock and Canovas. Different patterns of mixing of seawater with different hydrothermal fluids can lead to different evolutionary paths, but in general, the mixing favours formation of organic compounds from inorganic reactants. Hence, microbes could produce components of biomolecules simply by catalysis of reactions that are already energetically favoured. A fourth group of articles deals with the continental crust. Ingebritsen and Manning present a crustal-scale overview of permeability and argue that while there is a power–law relation between permeability and depth in tectonically active continental crust, some regions exhibit markedly higher permeabilities, probably as transients, while stable crust may decay to lower permeability. The specific issue of the relationship of hydrologic response to Geofluids (2010) 10, 1–2 doi: 10.1111/j.1468-8123.2010.00290.x

Frontiers in geofluids: editorial

[1] Recent spectroscopic detections of CH4 in the atmosphere of Mars are the first definitive observations of an organic compound on that planet. The relatively short photochemical lifetime of CH4 (∼300 years) argues for a geologically young source. We demonstrate here that low-temperature alteration of basaltic crust by carbon-bearing hydrothermal fluid can produce the required CH4 flux of 1 × 107 moles year−1, assuming conservative values for crustal permeability and oxygen fugacity as implied by Martian basaltic meteorites. The crustal thermal disturbance due to a single dike ∼1 × 1 × 10 km intruded during the past 104 years is capable of driving the alteration, if all carbon is supplied by magmatic degassing from a dike with only 50 ppm C. Atmospheric methane strongly suggests ongoing magmatism and hydrothermal alteration on Mars.

Formation of Methane on Mars by Fluid-Rock Interaction in the Crust

List of Contributors. Frontiers in geofluids: introduction (G. Garven, C. E. Manning and B. W. D. Yardley). Aqueous fluids at elevated pressure and temperature (A. Liebscher). Thermodynamic model for mineral solubility in aqueous fluids: theory, calibration and application to model fluid-flow systems (D. Dolejs and C. E. Manning). Metal complexation and ion association in hydrothermal fluids: insights from quantum chemistry and molecular dynamics (D. M. Sherman). Role of saline fluids in deep-crustal and upper-mantle metasomatism: insights from experimental studies (R. C. Newton and C. E. Manning). Potential of palaeofluid analysis for understanding oil charge history (J. Parnell). Spatial variations in the salinity of pore waters in northern deep water Gulf of Mexico sediments: implications for pathways and mechanisms of solute transport (J. S. Hanor and J. A. Mercer). Faults and fault properties in hydrocarbon flow models (T. Manzocchi, C. Childs and J. J. Walsh). Hydrostratigraphy as a control on subduction zone mechanics through its effects on drainage: an example from the Nankai Margin, SW Japan (D. M. Saffer). The interplay of permeability and fluid properties as a first order control of heat transport, venting temperatures and venting salinities at mid-ocean ridge hydrothermal systems (T. Driesner). Using seafloor heat flow as a tracer to map subseafloor fluid flow in the ocean crust (A. T. Fisher and R. N. Harris). The potential for abiotic organic synthesis and biosynthesis at seafloor hydrothermal systems (E. Shock and P. Canovas). Permeability of the continental crust: dynamic variations inferred from seismicity and metamorphism (S. E. Ingebritsen and C. E. Manning). Hydrologic responses to earthquakes and a general metric (Chi-Yuen Wang and Michael Manga). The application of failure mode diagrams for exploring the roles of fluid pressure and stress states in controlling styles of fracture-controlled permeability enhancement in faults and shear zones (S. F. Cox). Rates of retrograde metamorphism and their implications for crustal rheology (B. W. D. Yardley, D. E. Harlov and W. Heinrich). Fluids in the upper continental crust (Kurt Bucher and Ingrid Stober). Fluid-induced processes: metasomatism and metamorphism (A. Putnis and H. Austrheim). Fluid flows and metal deposition near basement /cover unconformity: lessons and analogies from Pb-Zn-F-Ba systems for the understanding of Proterozoic U deposits (M.-C. Boiron, M. Cathelineau and A. Richard). Magmatic fluids immiscible with silicate melts: examples from inclusions in phenocrysts and glasses, and implications for magma evolution and metal transport (Vadim S. Kamenetsky and Maya B. Kamenetsky). Index.

Frontiers in geofluids

Peridotite carbonation at the leading edge of the mantle wedge: OmDP Site BT1

The system NaAlSi3O8 (albite, Ab)-H2O offers a simple and tractable model to study the thermodynamics of the volatile constituent H2O in felsic magmas. Although it has been studied in this context for nearly 100 years, developing a comprehensive model that adequately describes the activity of H2O (
 $${a_{{H_2}O}}$$
 ) in hydrous albite liquids and vapors has proven challenging. There are several problems. First, $${a_{{H_2}O}}$$
 in hydrous liquids relies on melting experiments in the presence of mixed fluids with reduced H2O activity (H2O-CO2 and H2O-NaCl), but models of $${a_{{H_2}O}}$$
 in these coexisting fluids have lacked sufficient accuracy. Second, the role of the solubility of albite in H2O has been assumed to be negligible; however, it is important to take solubility into account at pressure (P) above 0.5 GPa because it becomes sufficiently high that H2O activity at the wet solidus is significantly less than 1. Third, the dry melting temperatures and wet solidus temperatures are inconsistent between the datasets. We address these issues by combining previous experimental work on T–
 $${X_{{H_2}O}}$$
 liquidus relations at 0.5–1.5 GPa with accurate activity formulations for H2O in mixed fluids (Aranovich and Newton, 1996, 1999). This yields isobaric T–
 $${a_{{H_2}O}}$$
 sections at 0.5, 0.7, 1.0 and 1.5 GPa. Data at each isobar were fit to cubic equations, which were used to derive the following equation for liquidus T as a function of $${a_{{H_2}O}}$$
 and P:

 $$T\left( {{a_{{H_2}O}},P} \right) = {m_0} + {m_1}{a_{{H_2}O}} + {m_2}a_{{H_2}O}^2 + {{m_3}a_{{H_2}O}^3}^\circ C$$
 
where T is °C, m
 0 = 1119.6 + 112.3P, m
 1 =–856.5–578.9P, m
 2 = 1004.1 + 952.9P, and m
 3 =–477.1–618.0P. The equation is valid at 0.5 < P < 1.5 GPa and T
 solidus < T < T
 dry melting. The nonzero solubility of albite in pure H2O is incorporated into the model to give the correct liquidus H2O activity when truncating the model equation in the limiting case where T → T
 solidus at a given pressure. This model equation reproduces both the liquidus-H2O contents and activities from the solubility measurements of Makhluf et al. (2016) in the binary system Ab-H2O at 1.0 GPa. The model equation also accurately reproduces the liquidus H2O activities from Eggler and Kadik (1979) and Bohlen et al. (1982) when the Aranovich and Newton (1999) activity formulation for CO2–H2O mixed fluids is applied to their datasets.

H 2 O activity in albite melts at deep crustal P-T conditions derived from melting experiments in the systems NaAlSi 3 O 8 -H 2 O-CO 2 and NaAlSi 3 O 8 -H 2 O-NaCl

Craig E. Manning

Papers

Frontiers in geofluids: editorial

Formation of Methane on Mars by Fluid-Rock Interaction in the Crust

Frontiers in geofluids

Peridotite carbonation at the leading edge of the mantle wedge: OmDP Site BT1

H 2 O activity in albite melts at deep crustal P-T conditions derived from melting experiments in the systems NaAlSi 3 O 8 -H 2 O-CO 2 and NaAlSi 3 O 8 -H 2 O-NaCl